A transmission that has vibration isolating rubber and that is supported by a vehicle body via a mount fixed to a cross member is conventionally known as a transmission for rear wheel drive vehicles which is connected to an engine (see, e.g., Patent Document 1). A power transmission device including a parking mechanism that locks an output shaft coupled to an output member of a speed change mechanism is also conventionally known as a power transmission device including a speed change mechanism (see, e.g., Patent Document 2). In this power transmission device, the output shaft of the speed change mechanism has a hub extending in the radial direction. A spline portion that couples the output shaft and the output member and a parking gear of the parking mechanism are arranged side by side in the axial direction on the outer periphery of the hub, and teeth of the parking gear and teeth of the splines are common teeth.